1. Field of the Invention
This invention relates to a method of treating a polymer compound by retaining the polymer compound and a chemical agent in a high-temperature and high-pressure condition so as to process the polymer compound into a thermoplastic resin or wax, and it relates to a treatment system for the polymer compound.
2. Description of the Related Art
In recent years, as the recycle and reuse of wastes are considered to be important in environmental problems, there is a high trend also to the recycling and reuse of polymer compounds. In such a trend, among these polymer compounds, thermoplastic resins can be fluidized by heating so that they can be molded again. Therefore, they are actually subjected to a material recycle (being recycled as a material).
In contrast, resins and elastomers such as thermosetting resins and crosslinked polymers cannot be fluidized by heating because the three-dimensional network among the molecules which cause poor processability of the polymer is not broken by heating. Thus, they are difficult to recycle. As a result, most of the thermosetting resins and crosslinked polymers are currently subjected to the waste disposal such as a land disposal, while part of them is treated in a thermal recycle (being recycled as a fuel).
However, the material recycle of the thermosetting resins and crosslinked polymers is increasingly researched and some methods thereon are suggested thus far.
For example, a method is suggested that the three-dimensional network structure among the molecules of a thermosetting resin is broken to process the resin into thermoplastic so as to recycle it as a thermoplastic resin by chemical agent in a high temperature and pressure. Another method is suggested that the main chain of a polymer is cut to have smaller molecules, thus processing the polymer into wax, which can be recycled as an additive to resins by chemical agent in a high temperature and pressure.
In order to commercially conduct such a method, a process is needed that the polymer is treated continuously. Extruders are suited for the process. This is because heat and pressure are needed to break the stable three-dimensional network structure among the molecules of a thermosetting resin and crosslinked polymer to process the resin and polymer into thermoplastic. The extruders can satisfy the conditions needed to process the polymer into thermoplastic. That is also true with the case of processing the polymer into wax.
Also, when processing it thermoplastic, an additive such as a thermoplastic resin or a chemical agent is usually added to the thermosetting resin or crosslinked polymer. In this case, the extruder allows the additive to be easily introduced thereinto.
Japanese patent application laid-open No. 8-300352 (related art 1) discloses a method that a primary amine or secondary amine as a coating film decomposer is mixed with a thermoplastic resin with a thermosetting resin coating film by using an extruder, where the thermoplastic resin is recycled at a temperature of 200 to 300° C. and a pressure of 10 to 100 kg/cm2.
Japanese patent application laid-open No. 2001-253967 (related art 2) discloses a method that a crosslinked polyethylene and water are supplied to an extruder, extruded under the conditions that allow water to be in a supercritical state or sub-critical state, i.e., at a temperature of 200 to 1000° C. and a pressure of 2 to 100 MPa, whereby a thermoplastic material is obtained.
Japanese patent application laid-open No. 2002-249618 (related art 3) discloses a method that a crosslinked polymer is extruded from an extruder to a reactor, a high-temperature and high-pressure fluid (a chemical agent) is supplied to the reactor by using a fluid-supply pump to react them to produce a reaction product, the reaction product and the unreacted chemical agent are introduced into a separator to separate the reaction product from the chemical agent, and the reaction product is discharged externally by using an extruder.
In the related art 1, the primary or secondary amine acts as the chemical agent to process the thermosetting resin or crosslinked polymer into the thermoplastic in the chemical reaction. In the related art 2, the water acts as well. However, these methods have the problem that the time required for the chemical reaction between the chemical agent and the thermosetting resin cannot be sufficiently secured in the extruder.
Also, in the related art 3, the reaction between the polymer compound and the chemical agent (high-temperature and high-pressure fluid) cannot be sufficiently conducted in the reactor since it is conducted in the reactor not in the extruder. Thus, this method has a limitation in enhancing the treatment capacity.